The invention relates to a gated control circuit for controlling an input signal available as a sequence of digital data words, including an adjusting member to which the input signal and a setting value are applied, a comparator circuit producing an output signal in accordance with the difference between the output signal of the adjusting member during the gating period and a desired value and a counter, from whose output signal the setting value is derived, to which a clock signal is applied and whose counting direction is controlled in dependence on the sign of the output signal of the comparator circuit.
Such a gated control circuit is disclosed in EP-OS No. 69 856. The gated control circuit is used for controlling the amplitude of the chrominance signal, formed by the picture chrominance signal and the colour synchronizing signal, of an FBAS-signal (television signal). As the chrominance information at the picture tube must be in the correct ratio relative to the luminance signal and the color synchronizing signal always is in a defined ratio to the luminance signal, the amplitude of the chrominance signal is controlled in dependence on the color synchronizing signal. The chrominance signal is applied as a digital signal to the prior art gated control circuit. The detected amplitude of the color synchronizing signal is stored in a hold circuit and the output signal of the hold circuit is applied to a comparator circuit. In the event of an output deviation the counter content is incremented or decremented, respectively by one unit during each gating period, independent of the value of the comparator circuit output signal. A large output deviation is consequently controlled more slowly than a small output deviation as the counting content is changed by the same amount in both cases.